What is the principal of operation of a transformer?

Why will a transformer not function normally when supplied from a dc source?

The principle of operation of a transformer is Faraday’s law of electromagnetic induction e=M di/dt. The physical basis of a transformer is mutual induction between two circuits linked by a common magnetic flux. A transformer consists of 2 inductive coils which are electrically separated but magnetically linked through a path of low reluctance. The two coils possess high mutual inductance. If one coil is connected to a source of alternating voltage, an alternating flux is set up in laminated core most of which is linked with other coil which produces mutually induced e.m.f. if the second coil circuit is closed, a current flows in it and electrical energy is transferred (entirely magnetically) from the 1^st coil to 2^nd coil.

In a transformer if dc source is applied then there will be no alternating flux rather than constant flux will be produced. So dφ/dt=0, from the Faraday’s law of electromagnetic induction E ∞ dφ/dt, then E=0, as no voltage is induced so it will be short circuited, a high current will be flowed through the winding which will cause damage of the winding.

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